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K. H. Baratz, J. W. McLaren, S. V. Patel, E. J. Winter, C. B. Nau, W. M. Bourne; Wavefront Analysis of the Corneal Surface in Deep Lamellar Keratoplasty versus Penetrating Keratoplasty. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3527.
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© ARVO (1962-2015); The Authors (2016-present)
To compare wavefront errors from the corneal surface after deep lamellar endothelial keratoplasty (DLEK) with wavefront errors after penetrating keratoplasty (PK).
Twenty eight eyes from 26 patients with corneal edema from Fuchs dystrophy were randomized to treatment with DLEK or PK. DLEK was performed with a 10 mm limbal incision, and all PKs were secured by using a double running suture technique. Corneal topography (Humphrey Atlas Corneal Topography System) was recorded before surgery and 1, 3, 6 and 12 months after surgery. All measurements in eyes with PK were done prior to final suture removal. Wavefront errors from the corneal surface were calculated over a 6-mm pupil by using VOLCT (Sarver and Associates, Inc., Celebration, FL) and expressed as Zernike polynomials to the 6th order. The root sum of squares of sphere, coma, and other high-order terms were compared within each group before and after surgery and between the two groups at each visit by using unpaired t-tests or signed-rank tests as appropriate, with Bonferroni correction for multiple comparisons.
Thirteen eyes were randomized to DLEK and 15 eyes to PK. Before surgery Zernike coefficients were not significantly different between the DLEK and PK corneas (p>0.30). Spherical aberration (Z40) was 0.26 ± 0.10 µm (mean ± SD) before and 0.36 ± 0.18 µm at 12 months after DLEK (p>0.9), and 0.25 ± 0.12 µm before and 0.46 ± 0.45 µm at 12 months after PK (p=0.36). Spherical aberration did not differ significantly at any examination after either DLEK or PK compared to preoperative (p>0.06). Coma (Z3-1, Z31) was 0.37 ± 0.33 µm before and 0.46 ± 0.35 µm at 1 month after DLEK (p=0.54), and 0.27 ± 0.19 µm before and 1.41 ± 0.45 µm at 1 month after PK (p=0.001). There were no changes in coma after DLEK through 12 months (p>0.9), whereas coma remained elevated at every visit after PK (p<0.006). Spherical aberration did not differ between treatments at any time after surgery (p>0.059) whereas coma was greater after PK than DLEK at all visits after surgery (p<0.003). Trefoil (Z3-3, Z33) was elevated at 1 month after DLEK (p<0.001), but not later, whereas it was elevated at all visits after PK (p<0.04). Trefoil was greater after PK than after DLEK at 6 months and 12 months (p<0.012).
Within the first year after DLEK, higher order wavefront aberrations do not change, other than transiently (trefoil). In contrast, after PK, coma and trefoil increase and remain elevated for up to a year. The effect of suture removal on higher order wavefront aberrations after PK has yet to be determined.
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